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In PPCISelLowering.cpp: PPCTargetLowering::LowerBUILD_VECTOR(), there is an optimization for certain patterns to generate one or two vector splats followed by a vector add or subtract. This operation is represented by a VADD_SPLAT in the selection DAG. Prior to this patch, it was possible for the VADD_SPLAT to be assigned the wrong data type, causing incorrect code generation. This patch corrects the problem. Specifically, the code previously assigned the value type of the BUILD_VECTOR node to the newly generated VADD_SPLAT node. This is correct much of the time, but not always. The problem is that the call to isConstantSplat() may return a SplatBitSize that is not the same as the number of bits in the original element vector type. The correct type to assign is a vector type with the same element bit size as SplatBitSize. The included test case shows an example of this, where the BUILD_VECTOR node has a type of v16i8. The vector to be built is {0, 16, 0, 16, 0, 16, 0, 16, 0, 16, 0, 16, 0, 16, 0, 16}. isConstantSplat detects that we can generate a splat of 16 for type v8i16, which is the type we must assign to the VADD_SPLAT node. If we do not, we generate a vspltisb of 8 and a vaddubm, which generates the incorrect result {16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16, 16}. The correct code generation is a vspltish of 8 and a vadduhm. This patch also corrected code generation for CodeGen/PowerPC/2008-07-10-SplatMiscompile.ll, which had been marked as an XFAIL, so we can remove the XFAIL from the test case. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209662 91177308-0d34-0410-b5e6-96231b3b80d8
11 lines
335 B
LLVM
11 lines
335 B
LLVM
; RUN: llc < %s -march=ppc32 -mcpu=g5 | grep vadduhm
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; RUN: llc < %s -march=ppc32 -mcpu=g5 | grep vsubuhm
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define <4 x i32> @test() nounwind {
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ret <4 x i32> < i32 4293066722, i32 4293066722, i32 4293066722, i32 4293066722>
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}
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define <4 x i32> @test2() nounwind {
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ret <4 x i32> < i32 1114129, i32 1114129, i32 1114129, i32 1114129>
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}
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